Slope Authentication at the Physical Layer

Ning Xie, Changsheng Chen

Abstract: Authentication is a key requirement for secure communications. In this paper, we consider authentication in a wireless system at the physical layer. There are two main authentication methods at the physical layer in the existing literature, authentication with time division multiplexed tag (Auth-TDM) and authentication with superimposed tag (Auth-SUP). However, there are drawbacks in the existing authentication methods. The Auth-TDM method requires additional bandwidth. The Auth-SUP method corrupts the entire data message. Moreover, regarding the purpose of authentication, both methods require additional complicated preprocessing such as channel estimation and message symbol recovery through demodulation and decoding. This paper proposes a new authentication method at the physical layer, referred to as slope authentication at the physical layer. The proposed method not only overcomes the aforementioned drawbacks but also is designed to be covert to the unware user, robust to interference, and secure for identity verification. The tradeoffs by considering different goals are discussed and analyzed in block-fading channels.